StreamWatch is supported and governed by: Albemarle County Fluvanna County The Nature Conservancy

1. Correlates of Biological Condition in Streams and Rivers of the Rivanna BasinJohn MurphyDirector, StreamWatch

2. StreamWatch is supported and governed by: • Albemarle County • Fluvanna County • The Nature Conservancy • Rivanna Conservation Society • Rivanna Water and Sewer Authority • TJ Planning District Commission • TJ Soil and Water Conservation District

3. Definition of Watershed A watershed, also called a catchment or basin, is the total area of land that funnels water to a given point on a stream or river.

4. Data • BIOLOGICAL: 207 biological samples from dozens of sites • HABITAT: In-stream and riparian zone • WATERSHED: Forest cover, population density, natural watershed variables • EFFLUENT

5. Watershed analysis The watershed draining to each monitoring site was delineated. Forest cover, population density, and other land use and natural features were quantified for each watershed. Examples: • The watershed draining to our Mechums River monitoring site is 69% forested. • Carys Creek watershed -85% forested

6. Benthic data quality • SW is a professional environmental monitoring program that leverages volunteer labor • Training, training, training • Frequent sampling = deep data set • Most family-level ID performed in lab by professional biologist • Side-by-side tests show no difference in results generated by StreamWatch and Virginia Department of Environmental Quality

7. Biological health assessment • Benthic scores reflect richness, evenness, trophic structure, and stress tolerance of bug community.

8. Biological health assessment • 5-6 samples/site!! • Average and minimum scores • Very good and good meet standards • Fair fails standards but could recover • Poor and very poor are probably persistently impaired

9. About ½ of streams meet standards

10. Population density–stream health model R2 = 0.89, p<0.001 (extremely strong correlation)

11. Benchmarks of biological condition ∙ Clean Water Act Line is associated with a density of about 55 people per square mile. This corresponds to approximately 1 dwelling per 27 acres (light exurban). (80% confidence interval: 30-95/sq mile [rural/exurban transition]).∙Persistent impairment line is associated with a density of about 210 people per square mile. This corresponds to approximately 1 dwelling per 7 acres (light suburban). (80% confidence interval: 120-365 people per square mile [heavy exurban/light suburban]).

12. Reality check

13. Correlation is not causation. What are the proximate causes of biological degradation? HABITAT DEGRADATION • Substrate (sedimentation, excess algae, etc.) • Light (too much) • Flow (too much, too little)

14. Correlation is not causation. What are the proximate causes of biological degradation? WATER QUALTIY DEGRADATION • Reduced oxygen levels • Toxic pollutants • Turbidity • Temperature

15. Correlation is not causation. What are the proximate causes of biological degradation? DISTURBING THE FOOD WEB • Nutrients; algae (too much or too little) • Leaves (too little) • Excess organic matter (cattle, septic, WW)

16. Correlation is not causation. What are the systemic causes of biological degradation? PRIMARY SUSPECTS (but no chain of causation yet) • Forest clearance and impervious surfaces, leading to . . . • Sediment runoff and/or . . . • Hydrologic alteration, leading to . . . • Stream bank erosion, sediment

17. In predicting stream biological health,watershed-scale land use appears to be a master variable. The effectiveness of localized stream protection practices is limited by the overarching effects of landscape disturbance throughout the stream’s watershed.

18. The half-full glass!